Origin of Species Variorum

→ moved first southward and afterwards backwards to the north, in unison with the changing climate, they will not 1866 1869 1872

during their long southern migration and re-migration northward, will 1859 1860 1861

→ during their long migrations to any great diversity of temperature; 1869 1872

to nearly the same climate, 1859 1860 1861

during their long migrations to any great diversity of temperature, 1866

→ they all migrated 1869 1872

is especially to be noticed, they will have kept 1859 1860 1861

they will all have migrated 1866

→ they have been modified; 1872

this we find has been the case; 1859 1860 1861 1866 1869

→ one with another, though 1866 1869 1872

though very 1859 1860 1861

→ or sub-species, and some as 1872

and some few are 1859 1860

and many are 1861

or sub-species, and some as certainly 1866 1869

→ each other on the several ranges. 1866 1869 1872

species. 1859 1860 1861

→ the foregoing illustration I have 1869 1872

illustrating what, as I believe, actually took place during the Glacial period, I 1859 1860 1861 1866

→ of our imaginary Glacial period, the 1869 1872

the 1859 1860 1861 1866

→ it is also necessary to assume that 1872

the foregoing remarks on distribution apply not only to strictly arctic forms, but also to 1859 1860 1861 1866

it is necessary also to 1869

→ were 1872

for some of these are 1859 1860 1861 1866 1869

→ world, for some of the species which now exist 1872

lower mountains and 1859 1860 1861

lower mountain-slopes and 1866 1869

→ lower mountain-slopes and on the plains 1872

plains 1859 1860 1861 1866 1869

→ are the same; and 1872

and 1859 1860 1861 1866 1869

→ they do at 1866 1869 1872

at 1859 1860 1861

→ from each other by 1866 1869 1872

by 1859 1860 1861

→ ocean; so that it may well be asked how the same species could then or previously have entered the two continents. 1872

ocean. 1859 1860 1861

ocean; so that it may well be asked how the same species could have entered two regions then so widely separated. 1866

ocean; so that it may well be asked how the same species could have entered the two continents then so widely separated. 1869

The

As the

arctic

forms,

forms

→moved first southward and afterwards backwards to the north, in unison with the changing climate, they will not have been exposed →during their long migrations to any great diversity of temperature;

and,

and

as →they all migrated in a body

together;

together,

consequently

....

their mutual relations will not have been much

disturbed,

disturbed.

and,

Hence,

in accordance with the principles inculcated in this volume,

they

these forms

will not have been liable to much modification. But with

our

the

Alpine productions, left isolated from the moment of the returning warmth, first at the bases and ultimately on the summits of the mountains, the case will have been somewhat

dif-

....

ferent;

different;

for it is not likely that all the same arctic species will have been left on

mountain ranges

mountain-ranges

distant

far distant

from each other, and have survived there ever since; they

will,

will

also,

also

in all

probability

probability,

have become mingled with ancient Alpine species, which must have existed on the mountains before the commencement of the Glacial epoch, and which during

its

the

coldest period will have been temporarily driven down to the plains; they will, also, have been

exposed

subsequently exposed

to somewhat different climatal influences. Their mutual relations will thus have been in some degree disturbed; consequently they will have been liable to modification; and →they have been modified; for if we compare the present Alpine plants and animals of the several great European

mountain-ranges,

mountain-ranges

→one with another, though many of the species

are

still remain

remain

identically the same, some

present

exist as

varieties, some

are ranked

....

as doubtful

forms,

forms

→or sub-species, and some as distinct yet closely allied

species

representative

representing

→each other on the several ranges.

In →the foregoing illustration I have

have assumed

assumed

that at

its

the

commencement →of our imaginary Glacial period, the arctic productions were as uniform round the polar regions as they are at the present day. But →it is also necessary to assume that

include many

many

sub-arctic and

....

some few

northern

....

temperate

forms,

forms

→were the same

round

the →world, for some of the species which now exist on the →lower mountain-slopes and on the plains of North America and

Europe;

Europe

→are the same; and it may be

reasonably

....

asked how I account for

the necessary

this

degree of uniformity

the sub-arctic and

northern

....

temperate forms round the world, at the commencement of the

Glacial

real Glacial

period. At the present day, the sub-arctic and northern temperate productions of the Old and New Worlds are separated from each other by the

Atlantic

whole Atlantic

Ocean and by the

extreme

....

northern part of the Pacific. During the Glacial period, when the

in-

....

habitants

inhabitants

of the Old and New Worlds lived

further

farther

southwards than →they do at present, they must have been still more completely separated →from each other by wider spaces of →ocean; so that it may well be asked how the same species could then or previously have entered the two continents.